CUCULLAA. 59 
and C, fibrosa have been considered by Briart and Cornet, Pictet and Campiche, 
Pictet and Renevier, Downes, and others, to belong to the same species. Sowerby’s 
glabra was a more rhomboidal example than his jibrosa, but a large series of 
specimens shows that there is no essential difference between the two. 
One of the specimens figured by Goldfuss (fig. le) as Area glabra 
(Sowerby) was regarded by d’Orbigny as distinct from the others (figs. 1 a, b, d), 
and named! by him Area subglabra. This name has been since generally adopted 
for the form found in the Aachen Greensand (Senonian). Goldfuss does not state 
from whence his figured specimens came, but gives in the text, as localities of the 
species, Quedlinburg, Coesfeld, Aachen, Kelheim, and Blackdown. J. Béhm? 
found, in the Museum of the Schloss Popplesdorf, examples labelled ‘“* England” 
which agree well with Goldfuss’ figures, and he believes that the figured 
specimens really came from Blackdown, and are the true Cucullea glabra, 
Sowerby. Briart and Cornet® also regard Goldfuss’ glabra as identical with 
Sowerby’s. The Blackdown specimens of (. glabra, Sowerby, certainly agree 
closely with the figures of Goldfuss (except fig. 1 c, in which the lateral teeth are not 
parallel to the hinge-margin, but this may have been a worn specimen) ; speci- 
mens and figures both differ considerably from the figures of the undoubted 
Aachen form given by Holzapfel;* the last-named author, however, does not 
appear to accept Bohm’s view, but takes the glabra of Goldfuss as the type of 
Area subglabra, @ Orbigny. 
Judging from MHolzapfel’s figures and description, Cucullea subglabra of 
the Aachen Greensand differs from C. glabra, Sowerby, in the shell being more 
convex and relatively higher; the hinge-line relatively shorter; the lateral teeth 
shorter, somewhat curved and not quite parallel to the hinge-line; the absence 
or indistinct nature of the radial ribs; and perhaps also in the less distinct carina. 
The arrangement of the teeth in C. glabra is similar to that in C. Miilleri, 
Holzapfel,’ from the Aachen Greensand; but in that form the shell is more 
rounded than in C. glabra, it is without a keel, the area is smaller, the hinge-line 
shorter, &e. 
C. Mailleana (d’Orbigny) (see p. 63) is relatively longer, more oblique—owing 
to the greater proportionate length of the posterior margin, and is ornamented with 
well-marked concentric grooves, the radial ribs being absent or indistinct. 
1 ¢ Prodr. de Pal.,’ vol. ii (1850), p. 244. 
* “Der Griinsand von Aachen und seine Molluskenfauna,” ‘ Verhand!. des naturh. Vereines der 
preussisch. Rheinl.,’ &., vol. xliv (1885), p. 92. 
3“ Descript. de la Meule de Bracquegnies,’’ ‘Mém. Cour. et Mém. des Sav. ¢trangers, Acad. 
Roy. Belg.,’ vol. xxxiv (1868), p. 55. 
* “« Die Mollusken der Aachener Kreide ” (‘ Paleeontographica,’ vol. xxxv, 1889), p. 206, pl. xxii, 
figs. 3, 5. 
5 Tbid., vol. xxv (1889), p. 209, pl. xxiii, fig. 1. 
